SEPTEMBER 19, 2026
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Case File

CVE-2026-66033

HIGH · CVSS 7.5 EPSS 0.37% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-24 · Last synced 2026-08-23

CyberRota Analysis

AI-Generated

OpenSSL versions prior to 1.11.1 are vulnerable to a pre-authentication integer underflow in the ssh2_cipher_crypt() function, which can be exploited by a malicious SSH server to crash any connecting client during the cipher negotiation phase. This vulnerability allows attackers to trigger an out-of-bounds read, leading to a process crash before authentication takes place. Organizations using affected versions of OpenSSL should prioritize patching to mitigate potential disruptions to their SSH services.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

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CVE
CVE-2026-66033
Severity
HIGH
CVSS
7.5
EPSS
0.37%
OpenSSL

Original NVD Description

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.

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